The world record was broken at the Effenaar music hall on Saturday night. An estimated 450 people joined the quiz, and that was already more than enough to account for.
Rotterdam recently hosted 355 people for a pop quiz. The next goal was to get 400 people together to play in the Effenaar, and they clearly succeeded.
The definitive total of attendees is still not made certain. That will only be known if the record has been officially approved.